Rock drill



Dec. 5, 1961 Filed Feb. 1, 1957 E. H. KURT ETAL 3,011,570

ROCK DRILL 2 Sheets-Sheet 1 INVENTORS EWALD H. KURT ROBERTL. THOMPSON THEIR ATTORNEY Dec. 5, 1961 E. H. KURT ETAL 3,011,570

ROCK DRILL Filed Feb. 1, 1957 2 SheetsSheet 2 -34 ea fi 42* l X 6 -3s 5s E a 5 K I Q .6 42 2 M-44 I y E 66 H6. 24 Q INVENTORS 58 EWALDH/(URT a 2 F085;? L. THOMPSON 42 1 44 Z! 3 i THEIR ATTORNEY United States Patent Ofiice 3,911,5219 Patented Dec. 5, 1951 3,011,570 ROCK DRILL Ewald H. Kurt and Robert L. Thompson, Phillipsburg, N.J., assignors to Ingersoll-Rand Company, New York, N.Y., a corporation of New Jersey Filed Feb. 1, 1957, Ser. No. 637,709 7 Claims. (Cl. 175-438) This invention relates to rock drills, and more particularly to the drill rod for a percussive type drill.

In drills of this type the piston is reciprocated by valving pressure fluid, such as air, to the opposite ends of the piston and a drill steel, generally of hexagonal cross sectional shape, has one end positioned within the drill motor to be struck repeatedly by the piston to actuate a bit connected on the other end of the steel. With this type of drilling, it is desirable to continuously angularly reposition the bit between succeeding blows of the piston. The more common method of doing this is to rotate the drill steel by means of a drill chuck which is in turn rotated by the piston, the piston being actuated rotationally as a result of longitudinal movement by means of a rifie bar having a spirally splined connection with the piston and a ratchet connection with the drill casing such that the piston rotates in one direction only.

; As the drilling proceeds and the depth of the hole increases the length of the drill steel is increased by adding additional sections of drill rod connected in end to end relation generally by threading the end of the steel into a tubular coupling of somewhat greater diameter than that of the steel.

There are several disadvantages associated with this method of transmitting both impact and rotary forces through a single rod or through a series of such rods connected in the manner specified. For example, tests have shown that stress waves set up in the drill rod by the piston striking the end of the rod are only partially expanded in actuating the bit into the work, some of the stress being reflected by the couplings and some of the stress waves being reflected at the bit. The reflected waves travel back and forth along the entire steel or in a section only, and tend to pull the steel apart at the couplings. These forces in addition to the torsional forces exerted on the steel and couplings result in early failure of the steel generally adjacent to an enlarged section of the steel such as occurs at a coupling.

It is accordingly one object of this invention to minimize the loss of energy in transmitting an impact force through a drill steel.

Another object is to provide such a device in which the rotary force is transmitted through one member and the impact force is transmitted through another member.

A further object is to provide a drill rod in sections of substantially uniform cross sectional area throughout their entire length.

Another object is to provide a rock drill combination with a sectional drill steel in which the sections are held together only by forces exerted at the opposite ends of the steel.

Still another object is to provide such a combination in which the steel is of substantially uniform cross sectional area throughout its entire length.

A further object is to provide a more efiective force transmitting device for transmitting impact and rotary forces to an earth boring implement.

Further objects will become obvious from the following specification and drawings, in which FIGURE 1 is a line diagram of a rock drilling unit provided with a preferred form of the invention,

FIG. 2 is a longitudinal sectional elevation showing the details of the force. transmitting device and a portion of the drill to which it is adapted,

FIG. 2A is a continuation of FIG. 2, and

FIGS. 3 and 4 are cross sectional views of FIG. 2A taken along the lines 3-3 and 4-4, respectively, looking in the direction of the arrows.

Referring to the drawings, and first to FIGURE 1, a preferred form of the invention is shown adapted, by way of example, to a self propelled track mounted drilling unit. This unit includes a tower 10 on which is slidably mounted a rotary head 12 connected to rotate a drill motor 14 of the percussive type connected to reciprocate a working implement, such as the drill bit 16, to drill a hole in the earth. The rotary head in rotating the drill serves to rotate the bit, and is mounted on a chain drive 13 driven by motor 19 for moving the drill longitudinally to feed the bit into the hole or Withdraw it therefrom.

Referring now to FIG. 2, the drill motor 14 shown is provided with a casing comprising a cylinder 29 and front head 22 with a guide piece 24 clamped therebetween. A piston 26 having ahead 28 fitted in the cylinder and a nose 3% slidable in the guide piece 24, is reciprocated by air under pressure valved alternately to the opposite surfaces of the head 28. The control of the how of such pressure fluid may be by any conventional valve structure (not shown) such as a flapper type valve, see for example the rock drill shown in US. Patent No. 1,750,- 323 which incidentally also shows the rifle bar-ratchet mechanism mentioned earlier as being a conventional means for rotating the piston to rotate the drill rod. In the particular drill shown, the hammer piston 26 does not directly strike the drill rod, but rather strikes an anvil block 32 fitted in the casing and slidable in a nose piece 34 threaded in and comprising part of the front head 22.

In accordance with an object of this invention, the rotary motion imparted to the drill bit, or working implement 16, is transmitted through an element separated from the element for transmitting the impact force of the drill motor. The torque transmitting rod 36 comprises a plurality of tubular sections 38 connected in end to end relation by means of couplings 40. Each coupling 49 is tubular in shape and has its opposite end portions 42 somewhat reduced in diameter and threaded into the internally threaded end portions 44 of the sections 38 joined thereby.

It is to be noted that with this coupling form that the maximum diameter of the coupling is substantially equal to the diameter of the tubular sections 38 such that the diameter of the torque transmitting rod S including the couplings 40, is substantially equal throughout its entire length such that there is no tendency of drill cuttings blown back along the exterior of the torque rod to wear away any particular area of the rod.

The lower end section 38' of the torque transmitting rod is interiorly splined at its free end 46 to receive the splines 48 on the shank 50 of the bit 16. Thus the bit is free tomove longitudinally relative to the torque rod 36 but is engaged against relative rotational movement so that the bit is rotated by the tube which in turn is rotated by the drill motor inasmuch as the rearmost coupling 40 is threaded in the nose piece 34.

With the particular bit construction shown, the shank 5-9 is shown as being separate from the bit body 52 and threadedly connected thereto such that the bit body may be discarded Without throwing away the shank 50. The rear end of the shank 59 is provided with a head 54 having a diameter in excess of the minimum or inside diameterof the splined portion 46 so that the bit cannot fall out of the end of the torque rod 35.

The impact force transmitting member, or rod, 55 comprises a plurality of rods 58 of somewhat smaller diameter than the internal diameter of the hollow torque rod 36- and is loosely slidable therein. The rods 58 are e) mounted in end to end relation with the rear end 61 of the rearmost rod section being positioned to abut the anvil block 32, whereas the front end 62 of the foremost rod section abuts the end of the bit shank 50. Means are provided to hold the ends of the rod in firm engagement with each other and the lower end of the rod 56 in engagement with the bit.

In the form of the invention shown this is accomplished by at all times exerting a downward force on the torque transmitting rod through the chain feed 18. More particularly by lowering the drill 14, either by gravity feed, or by a motor feed (not shown), the anvil block is forced against the end of the upper drill rod section 58 thereby constantly urging the rod sections into engagement with each other and with the bit which is held against forward motion by the work. The downward force can be applied also by an air spring such as disclosed in the patent application of W. A. Morrison, Serial No. 331,561, filed January 16, 1953, now Patent No. 2,810,549.

'It is to be noted that there are no coupling elements throughout the length of the impact transmitting member 56 and that it is of substantially uniform cross sectional form throughout its length so that there are no boundaries to reflect stress waves transmitted through this member.

If desired, some means may be provided to limit the longitudinal movement of a rod section 58 in the associated tubular section 38 and end coupling 49. The purpose of this is to prevent the rod section 58 from falling out of the tube section 38 when a new tube and rod section is being added to the ends of the torque and impact force transmitting rods. As shown, this means comprises forming the drill rod sections 58 of slightly greater diameter than that of the internal diameter of the coupling 46 and then reducing slightly the end portions of the rod sections 58 extending through the couplings, for example the portions of the rods between the points XX. This reduction in diameter is greatly exaggerated in the drawings for purposes of illustration. In practice this reduction is relatively small so that it does not materially affect the stated object of'providing an impact force transmitting member of substantially uniform cross sectional 'form throughout its entire length.

For the purpose of economy of manufacture and to permit interchangeability of elements, all rods 58 are of the same length and all rods 38 are of the same length. Each rod 58 is equal in length to the overall'length of a rod 38 and one coupling 40 secured thereon, except that the first and last couplings are shorter than the intermediate couplings to permit the rod 58 to extend beyond the rod 38 at both ends as shown. More particularly, the overall length of a rod 38 and the two shorter couplings 40 when secured thereto, is shorter than the length of a rod 58.

In the particular form of the invention shown air under pressure, such as the drill exhaust is conducted to the bottomof the drill hole to'blow cuttings free of the hole. In furtherance to this end the impact force transmitting rod 56 is provided with a central bore 64 throughout its entire length and communicated at its opposite ends with bores 66 and 68 inthe bit 16 and anvil block 32, respectively.

It is to be noted that this particular design of drill rod comprising an impact force transmitting rod and a torque transmitting rod incorporates in combination what is termed separable bit piece in patent application Serial No. 636,738, filed January 28, 1957, now abandoned, and accordingly the length of the bit 16 between the points YY is less than three times the length of the,

piston for the reasons specified in that application.

We claim:

1. The combination of a percussive type rock drill motor having a casing, means to rotate said casing, a piston reciprocable in said casing, an anvil block in the casing and engaged thereto against movement toward the rear end of the drill motor and having an end exposed to be struck by said piston, a working implement having a shank, a rod connected to be rotated by said casing to rotate the shank of said working implement, a rod having an end abutting said shank and its opposite end abutting said anvil block, one of said rods being hollow with the other of said rods rotationally and limitedly slidably located therein, said casing having abutting means independent of said hollow rod to constantly and positively exert force to the last said rods when said drill is operating.

2. The combination of a percussive type drill motor including a casing, means to rotate said casing, a reciprocable piston in said casing for striking a series of blows, a working implement having a shank, a hollow rod having one end adapted to interlockingly receive said shank of said working implement and having its opposite end connected to be rotated by said casing, a rod extending through said hollow rod and limitedly slidable therein when said shank of said working implement is disconnected, the second said rod being arranged to receive the force of such blows and transmit only such force to the working implement, and means for rotating said drill motor. 7

3. The combination of a fluid operated percussive type drill motor having a casing with a reciprocable piston therein for striking a series of blows, a working implement, a rotatable tube connected at one end portion to the drill motor and at its opposite end portion to said working implement for rotation thereof, the connection of the tube with the working implement being of the type to permit longitudinal movement therebetween, a plurality of rods each of which has an axially extending bore, said rods being positioned in end to end relation in said tube with said bores in communication with each other to provide for flow of fiuid therethrough, said working implement having passage means communicating with said bores to receive fluid from the latter and pass said fluid exteriorly of the working implement, and means independent of said tube and such fluid for positively and constantly urging all of said rods in the direction of said working implement whenever the drill motor is operating,

4. An impact and rotary force transmitting device for use with a percussive type rock drill motor, comprising a Working implement having one end portion provided with a force receiving surface, a rotatable tube having one end portion connected to said rock drill motor and the other end portion having a slidably interlocking con nection with said working implement for rotation thereof, and a rod slidable within 'said tube. having one end portion provided with a force receiving surface connected to said drill motor and the other end portion provided with a force transmitting surface engaging said force receiving surface of said working implement to transmit only longitudinal forces to said working implement, said tube including at least two sections, a connector to connect such sections in end to end relation, said connector defining a portion of. reduced inside dimensions in cross section in the tube, said rod being in unconnected sections corresponding in length roughly to the associated tube sections and located in end to end relation, and the rearmost rod section having an enlarged portion with an outer dimension in cross section greater than such reduced portion in said tube, the forward end of the enlarged portion being located near but rearward of said nected to said drill motor and the other end portion provided with a force transmitting surface engaging said force receiving surface of said working implement to transmit only longitudinal forces to said working implement, means to prevent said rod from sliding out of said tube When said working implement is disconnected from said tube, said tube being in a plurality of sections connected in end to end relation and the rod being in sections located in end to end relation, and means provided at each of said rod sections for limiting longitudinal movement in one direction of the rod section in the associated tube section.

6. The apparatus of claim 5 in which the tube has a portion of reduced inside dimensions in cross section and in which said last said means includes an enlarged portion of the rod having outer dimensions in cross section larger than the reduced portion of said tube.

-7. The apparatus of claim 5 in which the rod has a portion of enlarged outside diameter and wherein the tube is in a plurality of tubular sections positioned in end to end relation, and tubular shaped connecting elements are provided to connect said tubular sections to each other, said connecting elements having a maximum outer diameter substantially equal to the outer diameter of such tube and an inner diameter smaller than the inner diameter of said tubular sections and larger than the enlarged outer diameter portion of the rod.

References Cited in the file of this patent UNITED STATES PATENTS 1,006,661 Knapp Oct. 24, 1911 1,176,041 Dunbar Mar. 21, 1916 1,195,478 Knapp Aug. 22, 1916 1,559,709 Knapp Nov. 3, 1925 1,750,323 Lear Mar. 11, 1930 1,881,258 Bayles Oct. 4, 1932 2,583,979 Bassinger Feb. 12, 1952 2,661,928 Topanelian Dec. 8, 1953 

